1. Field of the Invention
The invention is directed to a vacuum seed meter for use with small grain having a screen located on the seed receiving side of a rotatable seed disc adjacent to seed attracting apertures.
2. Description of the Prior Art
Seed meters are used by agricultural seeding machines to control the rate at which seed is applied to a field. Seed meters for agricultural seeding machines can be divided into mechanical meters and air pressure meters. Mechanical meters use brushes, cups and/or finger pickups to single the seed. Air pressure seed meters use either positive or negative air pressure to direct seed to apertures formed in a rotating seed disc. The apertures are slightly smaller than the seed to be metered. The seed is attracted to the apertures by the passage of air therethrough and held in place by the air pressure. A sealing structure on the seed meter maybe used to isolate a portion of the rotatable seed disc so that the seed is released from the disc and falls out the outlet to the ground.
Air pressure seed meters are typically provided with plastic seed discs. These seed a discs encounter problems in metering smaller seeds such as wheat. Small grains require hundreds of small holes to obtain typical planting populations. These small holes plug easily with debris since the disc does not flex and the length of the hole is longer than the hole diameter. One solution has been proposed in U.S. Pat. No. 5,392,707 wherein a screen is inserted between two discs to form a seed disc.